Portable circular saw

ABSTRACT

The disclosed portable circular saw includes a motor having an axis, a housing enclosing the motor therein, a handle carried by the housing, an arbor operatively connected to the motor, the arbor having an axis of rotation substantially perpendicular to the motor axis, and a shoe supporting the housing thereon. The housing is inclined at an angle relative to the shoe. The handle is also disposed between the housing and the shoe. Preferably, the housing inclination angle is about 45°. The saw may also include a drive shaft disposed on the motor axis and a transmission mechanism connected to the arbor and the drive shaft. This transmission mechanism creates a torque in the rotational direction opposite to the rotational direction of the arbor. Preferably, the transmission mechanism includes a first gear disposed on the drive shaft, and a second gear disposed on the arbor, where the second gear meshes with the first gear. It is preferable that distance from the blade to the end of arbor is longer than distance from the blade to the drive shaft. The saw may also include a hook assembly attached to the handle at a position relative to the saw&#39;s center of gravity so that, when the circular saw is hung from the hook assembly, the handle pivots upward. Preferably, the hook assembly is a folding hook assembly. The hook assembly may include a barrel integrally attached to the handle, and a hook slidably connected to the barrel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/158,481, filed Sep. 22, 1998, now U.S. Pat. No. 5,930,903, which is acontinuation of U.S. application Ser. No. 08/866,790, filed May 30,1997, now U.S. Pat. No. 5,850,698.

FIELD OF THE INVENTION

The present invention relates to portable circular saws and, moreparticularly, in-line, end handle or worm drive portable circular saws.

BACKGROUND OF THE INVENTION

Generally, portable circular saws include a housing enclosing anelectric motor therein, a handle carried by the housing, a circular sawblade operatively connected to the electric motor, a blade case fixed tothe housing and adapted to enclose substantially the upper half of thesaw blade, a shoe for supporting the housing thereon, and a coverpivotally mounted on the housing and adapted to cover substantially thelower half of the saw blade projecting from the base plate. One commonarrangement for portable circular saws is the "spur gear" circular saw.In such circular saw, the motor drive rotation axis is coincident orsubstantially parallel to the blade rotation axis. One such circular sawis shown in U.S. Pat. No. 5,561,907.

Another common arrangement for portable circular saws is the worm drivecircular saw 100, as shown in FIG. 1. Unlike the spur gear circular saw,the motor axis 261 is substantially perpendicular to the blade rotationaxis 262. In addition, the worm drive saw has an elongated housing 26enclosing the motor. The main handle 263 is located at the end of themotor housing.

Traditionally, a worm gear transmission is used to operatively connectthe motor to the blade drive shaft perpendicularly rather than inparallel. However, bevel gear transmissions are also used for the samepurpose. Nevertheless, people still call saws with bevel geartransmissions "worm drive saws".

A worm drive saw is preferred over spur gear saws by some users becausethe housing is longer and narrower than a spur gear saw. The longerhousing is desirable for some applications, such as construction ofwooden frames, roofs, ceilings, floors, etc., that require a longerhousing to reach the workpiece.

The present invention offers two distinct advantages over the prior artworm drive saw. The first is improved balance and maneuverablility bylocating the center of gravity closer to the main handle.

The second addresses the condition that the motor axis is in the priorart generally coaxial to the user's arm when holding the saw by the mainhandle. The present invention effects improved handling by changing thehandle position.

Improved user handling is also accomplished by modifying the prior arttransmissions. FIG. 2 shows a prior art transmission. The motor 15 has adrive shaft 25 connected to a gear 251. This gear 251 meshes with abevel gear 31, which in turn is fixed to an arbor 21, which drives theblade 28 in a clockwise direction X, as is necessary for cutting. Thebevel gear 31 is located to the left of the drive shaft 25. In otherwords, the distance between the blade 28 and the bevel gear 31 issubstantially equal to or less than the distance from the blade 28 tothe drive shaft 25 providing a transmission of less weight and smallersize. However, the drive shaft rotates in a counterclockwise direction17 and creates a clockwise direction X, creating a clockwise reactiontorque 27.

It is also known in the prior art to provide a hanger on a circular sawfor hanging the saw from a joist where there are no table-like supportsand the saw is not in use. Prior art hangers have been proposed toorient the main handle vertically upward for easy accessibility, butthey increase the width or height of the saw. See, e.g., U.S. Pat. Nos.2,841,192 and 4,406,064.

SUMMARY OF THE INVENTION

The present invention provides a portable circular saw comprising amotor having an axis, a housing enclosing the motor therein, a handlecarried by the housing, an arbor operatively connected to the motor, thearbor having an axis of rotation substantially perpendicular to themotor axis, and a shoe supporting the housing thereon. The housing isinclined at an angle relative to the shoe when the saw is at the maximumdepth of cut setting. The handle is also disposed between the housingand the shoe. Preferably, the housing inclination angle is about 45°.

Another embodiment of the invention provides a portable circular sawhaving front and rear sections comprising a motor having an axis, ahousing enclosing the motor therein, a handle carried by the housing,the handle being disposed in the rear section of the saw, an arboroperatively connected to the motor, the arbor having an axis of rotationsubstantially perpendicular to the motor axis and being disposed in thefront section of the saw, and a shoe supporting the housing thereon. Therespective positions of the arbor and the handle define a direction ofelongation. The housing in turn is inclined at an angle relative to thedirection of elongation. Preferably, the handle is disposed between thehousing and the shoe. It is also preferable to provide a housinginclination angle of about 45° when the saw is at a maximum depth of cutsetting.

A further embodiment of the invention calls for a portable circular sawcomprising a motor having an axis and a drive shaft disposed along theaxis, a housing enclosing the motor therein, a handle carried by thehousing, an arbor for carrying a circular saw blade, the arbor having anaxis of rotation substantially perpendicular to the motor axis, atransmission mechanism connected to the arbor and the drive shaft, thetransmission mechanism creating a torque in a rotational directionopposite to the rotational direction of the arbor, and a shoe supportingthe housing thereon. Preferably, the transmission mechanism comprises afirst gear disposed on the drive shaft, and a second gear disposed onthe arbor, where the second gear meshes with the first gear. It is alsopreferable that the distance from the blade to the second gear isgreater than the distance from the blade to the drive shaft.

Another embodiment of the invention provides a portable circular sawhaving a center of gravity comprising a motor, a housing enclosing themotor therein and comprising a handle, an arbor operatively connected tothe motor, a shoe supporting the housing thereon, and a hook assemblyattached to the housing at a position relative to the center of gravity,wherein the center of gravity pivots about the hook assembly when thecircular saw is hung from the hook assembly so that the handle pivotsupward. Preferably, the hook assembly is a folding hook assembly. Thishook assembly may include a barrel integrally attached to the handle,and a hook slidably connected to the barrel. It may also include adetent cap attached to the barrel for holding the hook in a plurality ofradial positions, as well as a spring biasing the hook against thedetent cap.

A further embodiment of the invention calls for a portable circular sawcomprising a motor, a housing enclosing the motor therein, a handlecarried by the housing, the handle having a sidewall, an arboroperatively connected to the motor, a shoe supporting the housingthereon, and a folding hook assembly attached to the sidewall of thehandle so that, when the hook assembly is folded, the hook assemblysubstantially extends within the width of the shoe.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention according to the practical application of the principlesthereof, and in which:

FIG. 1 is a left side elevational view of a prior art portable circularsaw;

FIG. 2 is a partial cross-sectional view of the prior art saw along lineII--II of FIG. 1;

FIG. 3 is a left side elevational view of an embodiment of a portablecircular saw according to the present invention;

FIG. 4 is a partial cross-sectional view of the saw of FIG. 3 along lineIV--IV;

FIG. 5 is a right side elevational view of the saw of FIG. 3;

FIG. 6 is a partial top plan view of the saw of FIG. 5 along lineVI--VI;

FIG. 7 is a partial top plan view similar to the view of FIG. 6, showingan unfolded hook assembly;

FIG. 8 illustrates the manner in which the saw of FIG. 3 is hung from aboard;

FIG. 9 is a cross-sectional view of the hook assembly shown in FIG. 6along line IX--IX; and

FIG. 10 is a partial bottom plan view of the hook assembly of FIG. 9along line X--X and

FIG. 11 is a right side elevational view of a second embodiment of aportable circular saw according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is now described with reference to the accompanyingfigures, wherein like numerals designate like parts. Referring to FIG.3, a portable circular saw 10 is provided. The circular saw 10, like theprior art saw of FIG. 1, has a motor 15, an elongated housing 26enclosing the motor 15, and an arbor 21 for carrying a circular sawblade 28. The motor axis 261 is perpendicular to the axis of the arbor21 and to the blade rotation axis 262. In addition, the housing 26carries the main handle 263.

The circular saw 10 also has a shoe 300 supporting the housing 26.Preferably, the shoe 300 supports the housing 26 in such manner so thatthe housing 26 can be beveled relative to the shoe 300. In addition, theshoe 300 supports the housing 26 in a manner well known in the art sothat the housing 26 can be pivoted about pivot P in order to change theblade's depth of cut. Persons skilled in the art will recognize that thehousing inclination angle will increase as the depth of cut setting isdecreased.

It is also preferable to provide a fixed upper blade guard 264, attachedto the housing 26, for covering the upper part of the blade 28.Preferably, a movable lower blade guard 265 for covering the lower partof the blade 28 is also provided.

As shown in FIG. 3, illustrating the saw 10 in its maximum depth of cutsetting, the motor axis 261 is inclined relative to the shoe 300.Preferably, the motor axis 261 (and the housing 26) is inclined at abouta 45° angle at the maximum depth of cut setting and a 80° angle at theminimum depth of cut setting. Other ranges of inclination angles canalso be used. However, the 45° to 80° range is believed to maximize thehandling advantages of the present invention.

The main handle 263 is then disposed between the housing 26 and the shoe300. Accordingly, the rear end of the motor 15 is above and slightlyforward of the main handle 263. Persons skilled in the art willrecognize that, if the relative positions of the arbor 21 and the mainhandle 263 define a direction of elongation E, the housing 26 will beinclined relative to that direction of elongation.

This allows for improved balance due to the proximity of the motor'scenter of gravity CG to the main handle 263. It also allows for reducedoverall length compared to prior art models. In addition, use atstart-up is improved because the motor axis 261 is offset from the axisof the arm and as a result the torque is divided into side-to-side andtwisting torque rather than solely a twisting torque.

FIG. 4 shows a cross-sectional view of the saw 10. The motor 15 has adrive shaft 25 along the motor axis 261. The drive shaft 25, in turn, isconnected to a transmission mechanism 400. The transmission mechanism400 connects the drive shaft 25 and the arbor 21, and includes a gear251 disposed on the drive shaft 25, and a bevel gear 31 disposed on thearbor 21.

Unlike the prior art transmissions, the distance between the blade 28and the bevel gear 31 is greater than the distance between the blade 28and the drive shaft 25 such that the direction of the drive shaftrotation and arbor rotation are both clockwise. Such transmissionmechanism 400 creates a counterclockwise reaction torque 27c, i.e., inthe rotational direction opposite to the rotational direction(clockwise) of the arbor 21.

Referring to FIG. 5, a hook assembly 100 is integrally attached to thehandle 263. Persons skilled in the art will recognize that the hookassembly 100 can be integrally attached instead to the housing 26, asshown in FIG. 11, where like numerals refer to like parts. Preferably,the hook assembly 100 is a folding hook assembly. Referring to FIG. 9,the hook assembly 100 includes a hook 101 and a barrel 106 for attachingthe hook 101 to the saw.

Preferably, the hook 101 has a roll pin 102 attached at its end. Theroll pin 102 engages the detents 107 (FIG. 10) formed in a detent cap103. The detent cap 103 is fixed to the bottom of the barrel 106 andpermits the hook 101 to slide through it.

It is preferable to bias the hook 101 in the direction A so that theroll pin 102 is biased toward the detents 107 formed in the detent cap103. A possible mechanism for biasing the hook 101 includes a spacer105-slidably disposed within the barrel 106, which engages tags 108formed on the hook 101. A spring 104 is then disposed between the detentcap 103 and the spacer 105 so that the spring 104 pushes the spacer 105and hook 101 in the direction A.

Preferably, the detent cap 103 has detents 107 that allow the hook 101to be selectively positioned in two positions. In the first position,the hook 101 is positioned closely adjacent to the saw body for storage(see FIG. 6). Persons skilled in the art will note that the hookassembly 100 is disposed in such manner so that, when folded, the hookassembly 100 does not increase the height or width of the saw. Instead,the hook assembly 100 extends within the width of the shoe 300 whenfolded. Similarly, persons skilled in the art will note that the hookassembly 100 extends within the width of the housing 26 (shown in brokenlines in FIGS. 6 and 7).

In the second position, the hook 101 is preferably rotated through 90degrees from the first position and thereby extends away from the sawbody (see FIG. 7) so that the hook 101 may be hooked, for example, overa rafter 500 (see FIG. 8). The hook 101 may be selectively located ineither of the two positions by pushing the hook 101 and spacer 105against the bias of the spring 104 in the direction B to disengage theroll pin 102 from one of the detents 107. When disengaged, the hook 101is rotated through 90 degrees such that the roll pin 102 is now alignedwith the second of the two detents 107. The hook 101 is then releasedand the spring 104 then biases the roll pin 102 into the detent 107 asdescribed above.

It is preferable that the hook assembly 100 is located on the sawrelative to the center of gravity CG so that torque is created about thehook assembly 100 when the saw is hung from the hook assembly 100. Thetorque causes the center of gravity CG (and thus the saw) to pivot aboutthe hook assembly 100, so that the handle 263 pivots upwards for ease ofgrasping by the user. Accordingly, in the saw of FIG. 5, it ispreferable to attach the hook assembly 100 to a sidewall of the handle263.

Persons skilled in the art may recognize other features that can beadded to the embodiments described above, such as providing an auxiliaryhandle above the center of gravity or above the arbor. Similarly,persons skilled in the art may recognize other alternatives to the meansdisclosed herein. However, all these additions and/or alterations areconsidered to be within the scope of the claims underneath.

We claim:
 1. A portable circular saw having a center of gravitycomprising:a motor having an axis; a housing enclosing the motortherein; a handle carried by the housing; an arbor for carrying a sawblade, said arbor being operatively connected to the motor and having anaxis of rotation substantially perpendicular to the motor axis; and ashoe pivotally supporting the housing thereon, the housing pivotingrelative to the shoe about a pivoting axis which is substantiallyparallel to the arbor axis; wherein the housing is inclined at an anglerelative to the shoe, part of the handle is disposed behind the arboraxis, between the housing and the shoe, and within said angle, and thepivoting axis is disposed in front of the arbor axis.
 2. The saw ofclaim 1, wherein the angle is about 45°.
 3. The saw of claim 1, furthercomprising a hook assembly attached to said handle.
 4. The saw of claim3, wherein the hook assembly is attached to said handle at a positionrelative to the center of gravity so that, when the circular saw is hungfrom said hook assembly, the handle pivots upward.
 5. The saw of claim3, wherein the hook assembly is a folding hook assembly.
 6. The saw ofclaim 5, wherein the handle has a sidewall, the shoe has a width, andthe hook assembly is attached to said sidewall of said handle so that,when said hook assembly is folded, the hook assembly substantiallyextends within the width of said shoe.
 7. The saw of claim 5, whereinthe handle has a sidewall, the housing has a width, and the hookassembly is attached to said sidewall of said handle so that, when saidhook assembly is folded, the hook assembly substantially extends withinthe width of said housing.
 8. The saw of claim 3, wherein the hookassembly comprises a barrel integrally attached to said handle, and ahook slidably connected to said barrel.
 9. The saw of claim 8, whereinthe hook assembly further comprises a detent cap attached to said barrelfor holding the hook in a plurality of radial positions.
 10. The saw ofclaim 9, wherein the hook assembly further comprises a spring biasingsaid hook against said detent cap.
 11. The saw of claim 9, wherein thehook assembly further comprises biasing means for biasing said hookagainst said detent cap.
 12. The saw of claim 1, further comprising adrive shaft disposed along the motor axis, and a transmission mechanismconnected to said arbor and said drive shaft.
 13. The saw of claim 12,wherein said transmission mechanism creates a torque in rotationaldirection opposite to rotational direction of said arbor.
 14. The saw ofclaim 12, wherein said transmission mechanism comprises:a first geardisposed on said drive shaft; and a second gear disposed on said arbor,said second gear meshing with said first gear.
 15. The saw of claim 14,wherein distance from the blade to the second gear is greater thandistance from the blade to the drive shaft.
 16. The saw of claim 1,further comprising a hook assembly attached to said housing.
 17. The sawof claim 16, wherein the hook assembly is attached to said housing at aposition relative to the center of gravity so that, when the circularsaw is hung from said hook assembly, the handle pivots upward.
 18. Thesaw of claim 16, wherein the hook assembly is a folding hook assembly.19. The saw of claim 18, wherein the shoe has a width and, when saidhook assembly is folded, the hook assembly substantially extends withinthe width of said shoe.
 20. The saw of claim 16, wherein the hookassembly comprises a barrel integrally attached to said housing, and ahook slidably connected to said barrel.
 21. The saw of claim 20, whereinthe hook assembly further comprises a detent cap attached to said barrelfor holding the hook in a plurality of radial positions.
 22. The saw ofclaim 21, wherein the hook assembly further comprises a spring biasingsaid hook against said detent cap.
 23. The saw of claim 21, wherein thehook assembly further comprises biasing means for biasing said hookagainst said detent cap.
 24. The saw of claim 1, wherein a first planesubstantially perpendicular to a second plane defined by the shoeintersects the shoe, the handle and the housing, in that order, when thesaw is at a maximum depth of cut setting.
 25. The saw of claim 1,wherein said angle being less than about 90°.
 26. The saw of claim 1,wherein the distance between the pivoting axis and the shoe is smallerthan the distance between the arbor axis and the shoe.